Art of War Chapter 13: The Use of Spies — 用间 Explained

What Chapter 13 is about

Chapter 13, The Use of Spies (用间, Yòng Jiàn), is the final chapter of the Art of War, and it is the chapter in which the book argues that foreknowledge comes from people, not from omens: knowing the enemy's present situation in advance is what lets a wise sovereign and a good general strike and conquer, and that foreknowledge can only be obtained through human intelligence. The chapter distinguishes five kinds of spies, explains how each is used, and insists that intelligence must be handled with intimacy, generous reward, and secrecy.

Its deeper teaching, recorded in the site's chapter description, is that foreknowledge cannot be obtained from spirits, gods, or past experience, and can only be obtained through human intelligence: spies. In the words of the registered one-line purpose, "Foreknowledge is everything — what can only be learned through intelligence."

Identity and translation boundary

The chapter is registered as 用间 (Yòng Jiàn), English "The Use of Spies," slug the-use-of-spies, chapter 13 of thirteen. The Chinese Text Project, the registered primary-text source for this chapter, presents the received text under the traditional spelling 用間.

A working gloss on the title: 用间 combines 用 (to use/employ) with 间 (read jiàn in this compound, in the sense of "spy"/"intermediary"; the character 间/间 is also read jiān meaning "between/among"), so the compound renders "the employment/use of spies"; the chapter's own enumeration, 五间 (Wǔ Jiàn), names the five kinds of spies. This is a working gloss and is not presented as a settled translation.

English editions render the title variously. The site's registered label is "The Use of Spies"; the SEO-082 evidence shows the legacy chapter-13 routes carried "The Use of Spies" and "Employment of Spies." No single printed edition is registered as canonical, so this page follows the established site convention of paraphrase with quotation limited to at most 25 words.

Source and translation notes

The registered primary source for this page is the Chinese Text Project page for the chapter, https://ctext.org/art-of-war/use-of-spies, which presents the received Chinese text under the title 用間 together with an English translation attributed to Lionel Giles (1910); the page records the URN ctp:art-of-war/use-of-spies. This locator is the only registered per-chapter primary-text locator in the SEO-112 phase-b record, and it is used here as registered.

The Oriens data record labels the chapter 用间 (Yòng Jiàn), English "The Use of Spies," with the slug the-use-of-spies, and records the one-line purpose "Foreknowledge is everything — what can only be learned through intelligence." For the reader's orientation, this page maps the chapter's content into five parts: the cost framing and the height-of-inhumanity argument; the foreknowledge definition and its exclusions; the five kinds of spies and their roles; the handling and rewarding of intelligence sources; and the converted spy's pivotal coordinating role and the chapter's closing argument. This is an editorial navigation map for this page, not a statement about how the ctext page itself numbers or labels the text.

A translation note on the five classes: the received text on the ctext page writes the five kinds of spies as 鄉間, 內間, 反間, 死間, and 生間, which the Giles rendering names Local, inward, converted, doomed, and surviving spies. The Oriens data record registers the same five classes with the Chinese terms 因间, 内间, 反间, 死间, and 生间 (local, internal, converted, expendable, surviving). The first class appears as 鄉間 (xiang jian) in the received text and as 因间 (yin jian) in the data record; both are rendered "local spies" in English, and the difference is recorded here as a textual-variant note, not a settled reading.

Historical context

The Art of War is traditionally attributed to Sunzi (Sun Tzu), a figure of ancient China, but the traditional dating (roughly the sixth to fifth centuries BCE) is a traditional attribution and is not asserted here as a settled fact. The received text is a book of thirteen chapters; Chapter 13 is the thirteenth and final chapter in that sequence. The Chinese Text Project catalogues the work under the School of the Military (兵家) in its Pre-Qin and Han corpus, alongside works such as the Wu Zi and the Liu Tao.

This page presents no biography of Sunzi, no settled dating, and no account of the courts or kingdoms the text is traditionally tied to; such claims would require their own sources and are out of scope here.

Foreknowledge and what the text excludes

The chapter's intellectual center is its definition of foreknowledge. The text states that what enables the wise sovereign and the good general to strike and conquer is foreknowledge, and that this foreknowledge cannot be elicited from spirits, obtained inductively from experience, nor by deductive calculation; knowledge of the enemy's dispositions can only be obtained from other men. In other words, the chapter rejects spirits, divination, and simple analogy with past events as substitutes for information gathered from people who know what is happening.

That exclusion is a defining boundary of the chapter. A commander cannot reason from a general pattern alone; a decision needs timely, situated evidence. The text therefore places intelligence inside strategy itself: information is valuable because it changes what a ruler or commander can decide before committing force.

The five kinds of spies and their roles

The chapter names five kinds of intelligence sources, registered in the data record as local spies (因间), internal spies (内间), converted spies (反间), expendable spies (死间), and surviving spies (生间). These are not five interchangeable labels; each has a different source of access and a different role in the chapter's wider intelligence system.

Local spies employ the services of the inhabitants of a district.

Internal spies make use of officials of the enemy.

Converted spies are the enemy's own spies, got hold of and used for one's own purposes.

Expendable (doomed) spies are used to do certain things openly for purposes of deception, allowing one's own spies to know of them and report them to the enemy.

Surviving spies bring back news from the enemy's camp.

The text states that when the five kinds of spy are all at work, none can discover the secret system — a state it calls "divine manipulation of the threads" and the sovereign's most precious faculty. The deeper point is coordination: a single report can be wrong, partial, or manipulated, and a system that compares different sources can distinguish a useful signal from a planted story.

Handling and rewarding spies

The chapter is as much about how to treat intelligence sources as about how to recruit them. The text states that no one in the whole army should maintain more intimate relations than with spies, none should be more liberally rewarded, and in no other business should greater secrecy be preserved. It also sets requirements on the handlers: spies cannot be usefully employed without a certain intuitive sagacity, cannot be properly managed without benevolence and straightforwardness, and without subtle ingenuity of mind one cannot make certain of the truth of their reports. The text urges subtlety: "Be subtle! be subtle! and use your spies for every kind of business."

The chapter's secrecy rule is explicit and harsh. It states that if a secret piece of news is divulged by a spy before the time is ripe, the spy must be put to death together with the man to whom the secret was told. This is presented as the text's own statement in its military context; this page neither endorses nor extends it.

The chapter also describes how intelligence work begins in practice: whether the object be to crush an army, to storm a city, or to assassinate an individual, the text says it is always necessary to begin by finding out the names of the attendants, the aides-de-camp, and the door-keepers and sentries of the general in command. It describes the conversion method: the enemy's spies who come to spy on us must be sought out, tempted with bribes, led away, and comfortably housed, and thus they become converted spies available for one's service. Both passages are presented as the received text's own military doctrine, not as instructions for modern conduct.

The converted spy and the coordinated system

The text gives the converted spy a pivotal role. It states that through the converted spy the commander can acquire and employ local and inward spies, cause the doomed spy to carry false tidings to the enemy, and use the surviving spy on appointed occasions; the end of spying in all its five varieties is knowledge of the enemy, and this knowledge is derived, in the first instance, from the converted spy — hence the converted spy must be treated with the utmost liberality. The value is not simply that one person changes sides; it is that the converted source can help the commander identify and coordinate other channels of intelligence.

This is also why the chapter repeatedly emphasizes trust, secrecy, and generous treatment. Intelligence work depends on human relationships, and the information system fails when sources cannot safely communicate or when their contribution is treated as disposable.

The chapter cites historical precedent for the power of such intelligence: the rise of the Yin dynasty was due to Yi Zhi (伊摯), who had served under the Xia, and the rise of the Zhou dynasty was due to Lu Ya (呂牙), who had served under the Yin. These figures are presented exactly as the received text presents them; no biographical lore is added. The chapter closes by stating that the enlightened ruler and the wise general will use the highest intelligence of the army for purposes of spying and thereby achieve great results, and that spies are a most important element in war because on them depends an army's ability to move.

The military and ethical boundary

The chapter's own ethical argument is about the cost of war. It opens by counting what a campaign already costs — a host of a hundred thousand men, great distances, heavy loss on the people and a drain on the resources of the state, hostile armies facing each other for years for a victory decided in a single day — and then calls it the height of inhumanity to remain in ignorance of the enemy's condition because one grudges the outlay of a hundred ounces of silver in honors and emoluments. One who acts thus, the text says, is no leader of men, no present help to his sovereign, no master of victory.

The boundary of this page is that the chapter's espionage content belongs to ancient warfare between states. The cost framing, the secrecy rules, and the harsh passages (including the premature-disclosure death rule) are the text's own statements addressed to a ruler and general weighing war. This page provides no operational espionage instructions for modern wrongdoing, makes no business guarantee, and does not extend the methods to any modern setting.

Misreading boundary: what this chapter is not

Not a business or career success formula. This is a military text about war between states. No business-success, leadership-success, or guaranteed-outcome claim is made here or attributed to the text.

Not a modern espionage manual. The chapter describes ancient military intelligence methods; this page does not provide operational instructions for espionage, covert conduct, or other wrongdoing in a modern setting.

Not a promise about foreknowledge. The text limits foreknowledge to information from people who know the enemy's present situation; it explicitly excludes spirits, divination, and analogy with past events, and this page asserts no outcome from intelligence beyond what the text claims for a wise sovereign and a good general.

The pivotal source is the converted spy, not a generic "double agent." The data takeaway phrase "Double agents are the most valuable intelligence source" is a loose modern gloss; the received text names the pivotal source as the converted spy (反间), and this page renders the chapter's own term as "converted spy."

The first class is not a settled spelling. The received text writes the local spies as 鄉間 and the data record registers them as 因间; both render "local spies" in English, and the difference is a recorded textual-variant note, not a settled reading.

The harsh passages are the text's own, not a recommendation. The premature-disclosure death rule and similar statements are presented as the received text's military doctrine, without endorsement or extension.

No unsupported biography or identity facts. This page presents no birth, death, or court dates for Sunzi and no alternate romanization of the chapter title; the registered identity is 用间 (Yòng Jiàn), and the traditional attribution is marked as traditional and unsettled.

A restrained modern reading

Reading this chapter in the present day, the most defensible transfer is procedural rather than prescriptive. The chapter's durable lesson is to treat information as a system: define the question, seek information from more than one vantage point, cross-check independent sources, keep the distinction between evidence and interpretation visible, and connect information to a concrete decision. In business or research, the five categories can serve as a loose comparison for different evidence sources — observation, informed insiders, competing signals, deliberately public positioning, and validated findings — but the comparison is bounded: modern organizations must respect privacy, law, consent, and professional ethics, and the ancient military vocabulary should not be used to justify covert or unlawful conduct.

This reading is explicitly interpretation. The chapter itself is about intelligence in war between states, and its handling and reward rules are addressed to a ruler and a general weighing those stakes. Borrowing its habit of cross-checking sources and separating evidence from interpretation for a non-military situation is a use of the text, not a statement about what the ancient author meant to teach, and it carries no promise of success in any modern setting.